Heat-dissipation unit with heat-dissipation microstructure and method of manufacturing same

ABSTRACT

A heat-dissipation unit with heat-dissipation microstructure and method of manufacturing the same is disclosed. The heat-dissipation unit with heat-dissipation microstructure includes a main body internally defining a chamber; a wick structure formed on an inner surface of the chamber; and at least a SiO 2  nano thin film coated on the wick structure. The SiO 2  nano thin film is formed of a plurality of SiO 2  nanograins, and is coated on the wick structure of the heat-dissipation unit through the sol-gel process. With the at least one layer of SiO 2  nano thin film coated on the wick structure, it is able to upgrade the heat dissipation performance of the heat-dissipation unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. patent application Ser.No. 12/938,342, filed on Nov. 2, 2010, titled Heat-Dissipation Unit withHeat-Dissipation Microstructure and Method of Manufacturing Same,listing Ying-Tung Chen, as inventor. This application claims thepriority benefit of Taiwan patent application number 098143582 filed onDec. 18, 2009.

FIELD OF THE INVENTION

The present invention relates to a heat-dissipation unit withheat-dissipation microstructure and method of manufacturing same; andmore particular to a heat-dissipation microstructure being coated with aSiO₂ nano thin film and a method of manufacturing the same.

BACKGROUND OF THE INVENTION

While many of the currently available electronic apparatus have largelyincreased operational speed, the electronic elements thereof alsoproduce a large quantity of heat. It is very important to timely removethe heat produced by the electronic elements and chips from theelectronic apparatus, lest the electronic apparatus should becomedamaged due to overheating caused by accumulated heat therein.

To properly remove the produced heat, heat sinks or various kinds ofthermal modules and cooling fans can be provided on the electronicelements and the chips, so as to cool the electronic elements and chipsand to dissipate heat therefrom. Among others, heat pipe is thecurrently most effective and popular means for heat transfer. A heatpipe can be made of a copper material or an aluminum material to have aninternal chamber. A wick structure is formed on an inner surface of thechamber, and a working fluid is provided in the chamber. After thechamber is vacuumed, an open end of the heat pipe is sealed to therebygive the heat pipe a vacuumed and completely closed chamber. The heatpipe can be configured in different shapes, but is most frequentlyconfigured as a tube or a flat hollow plate. The wick structure in theheat pipe has significant influence on the heat transfer ability of theheat pipe, particularly for the flat heat pipe, which is also referredto as a vapor chamber. An ideal wick structure must be able to providestrong capillary force while having a small flow resistance. However,these two requirements are opposed to each other in terms of structure.To solve this conflicting condition, the only way is to perform surfacemodification in order to change the characteristics of the surface ofthe material. Generally, the surface modification is aimed to change thewick structure for the latter to have wettability and accordinglyincreased capillary force. One of the most effective methods to modifythe material surface for the same to have wettability is to produce anano-sized microstructure. The nano-sized microstructure can be producedin different processes, including etching process and chemical vapordeposition (CVD) process. In the etching process, a chemical solution isused to corrode the material surface and thereby form a recessedmicrostructure thereon. However, the etching process has thedisadvantages of not easy to control the etching rate and tending tocause environmental pollution. On the other hand, the CVD process candeposit a nano-sized structure on the material surface but not in themicro pores in the wick structure, and therefore fails to achieve thepurpose of surface modification.

Taiwan Invention Patent Number I292028 discloses a heat pipe and amethod manufacturing the same. The heat pipe includes a hollow tubularenclosure having two sealed ends, a wick structure formed on an innerwall surface of the hollow tubular enclosure and having a hydrophiliccoating formed thereon; and a working fluid filling the wick structureand being sealed in the tubular enclosure. The hydrophilic coating canbe formed of a material selected from the group consisting of nano-TiO₂,nano-ZnO, nano-Al₂O₃, and any combination thereof, and has a thicknessranged between 10 nm and 200 nm, preferably ranged between 20 nm and 50nm.

According to Taiwan Invention Patent Number I292028, the tubularenclosure is formed on an outer wall surface with a thermally conductivecoating, which can be formed of a material selected from the groupconsisting of carbon nanotube, nano-copper, nano-aluminum, andcopper-aluminum alloy nano thin film; and has a thickness ranged between10 nm and 500 nm, preferably ranged between 20 nm and 200 nm.

The wick structure includes carbon nano capsules and carbon fibers, andhas a thickness ranged between 0.1 mm and 0.5 mm, and preferably rangedbetween 0.2 mm and 0.3 mm.

And, the method of manufacturing the heat pipe includes the steps ofproviding a hollow tubular enclosure; forming a wick structure on aninner wall surface of the hollow tubular enclosure; forming ahydrophilic coating on a surface of the wick structure; andvacuum-sealing an adequate quantity of working fluid in the hollowtubular enclosure.

The inner and outer wall surfaces of the hollow tubular enclosure aresubjected to a laser texturing process in advance.

The hydrophilic coating is formed through chemical vapor deposition(CVD), plasma enhanced CVD, sputtering deposition, or co-sputteringdeposition.

The above-mentioned prior art heat pipe manufacturing method requiresequipment and instruments that are highly expensive to inevitablyincrease the manufacturing cost of the heat pipe, and therefore has thefollowing disadvantages: (1) it can only form deposition on the surfaceof a workpiece; (2) it is not suitable for mass-production; (3) itrequires high manufacturing cost; and (4) it is implemented usingexpensive equipment.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a method ofmanufacturing a heat-dissipation unit with heat-dissipationmicrostructure, so as to increase the heat transfer efficiency of theheat-dissipation unit.

Another object of the present invention is to provide a heat-dissipationunit with heat-dissipation microstructure.

To achieve the above and other objects, the heat-dissipation unit withheat-dissipation microstructure includes a main body internally defininga chamber, a wick structure formed on an inner surface of the chamber;and at least a SiO₂ nano thin film coated on a surface of the wickstructure. The SiO₂ nano thin film is formed of a plurality of SiO₂nanograins; and the heat-dissipation unit can be any one of a vaporchamber, a heat pipe, and a loop heat pipe. The wick structure is formedof a material selected from the group consisting of copper, aluminum,nickel, and stainless steel. The SiO₂ nanograins forming the SiO₂ nanothin film have a grain size ranged between 1 nm and 100 nm.

To achieve the above and other objects, the method of manufacturingheat-dissipation unit with heat-dissipation microstructure includes thesteps of providing a heat-dissipation unit internally defining achamber; forming a wick structure on an inner surface of the chamber ofthe heat-dissipation unit; coating at least an oxide nano thin film on asurface of the wick structure; drying and annealing the wholeheat-dissipation unit; sintering the wick structure having the oxidenano thin film coated thereon, so that the oxide nano thin film isstably attached to the surface of the wick structure; vacuuming thechamber of the heat-dissipation unit; injecting a working fluid into thechamber; and sealing an open end of the heat-dissipation unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present inventionto achieve the above and other objects can be best understood byreferring to the following detailed description of the preferredembodiments and the accompanying drawings, wherein

FIG. 1 is a cross-sectional view of a heat dissipation unit withheat-dissipation microstructure according to a first embodiment of thepresent invention;

FIG. 1a is a cross-sectional view of a heat dissipation unit withheat-dissipation microstructure according to a second embodiment of thepresent invention;

FIG. 1b is a fragmentary cross-sectional view of a heat dissipation unitwith heat-dissipation microstructure according to a third embodiment ofthe present invention;

FIG. 2 is a cross-sectional view of another type of heat-dissipationunit with heat-dissipation microstructure according to the presentinvention;

FIG. 3 is a schematic sectional view of a metal grain for forming a wickstructure according to an embodiment of the present invention, and anoxide nano thin film coated thereon;

FIG. 3a is an enlarged view of the circled area 3 a of FIG. 3;

FIG. 4 is a scanning electron microscope (SEM) image of a wick structureaccording to an embodiment of the present invention;

FIG. 5 is an SEM image of an oxide nano thin film coated on the wickstructure according to an embodiment of the present invention;

FIG. 6 is another SEM image of the oxide nano thin film coated on thewick structure according to an embodiment of the present invention;

FIG. 7 is a flowchart showing the steps included in a first embodimentof a method of manufacturing heat-dissipation unit with heat-dissipationmicrostructure according to the present invention;

FIG. 8 is a schematic sectional view showing the forming of at least anoxide nano coating on the wick structure according to the method of thepresent invention;

FIG. 9 is a flowchart showing the steps included in a second embodimentof the method of manufacturing heat-dissipation unit withheat-dissipation microstructure according to the present invention;

FIG. 10 is a flowchart showing the steps included in a third embodimentof the method of manufacturing heat-dissipation unit withheat-dissipation microstructure according to the present invention;

FIG. 11 is another schematic sectional view of the metal grain forforming the wick structure according to another embodiment of thepresent invention, and two oxide nano thin films coated thereon; and

FIG. 11a is an enlarged view of the circled area 11 a of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferredembodiments thereof and with reference to the accompanying drawings. Forthe purpose of easy to understand, elements that are the same in thepreferred embodiments are denoted by the same reference numerals.

Please refer to FIGS. 1, 1 a, 1 b, 2, 3, 3 a, 11, and 11 a. Aheat-dissipation unit 1 according to the present invention includes amain body 11 internally defining a chamber 111, a wick structure 2provided on an inner surface of the chamber 111, and at least a SiO₂nano thin film 3 coated on a surface of the wick structure 2. The SiO₂nano thin film 3 is formed of a plurality of SiO₂ nanograins 31.

The wick structure 2 can be a grooved wick structure as shown in FIG. 1a, a mesh wick structure as shown in FIG. 1b , a copper-powder sinteredporous wick structure as shown FIG. 1, or a composite wick structureincluding any combination of the grooved, mesh, and copper-powdersintered porous wick structures (not shown).

The following explanation of the illustrated embodiment of the presentinvention is based on the sintered copper porous wick structure as shownin FIG. 1. More specifically, the wick structure 2 is formed bysintering a plurality of metal grains 12. The metal grains 12 areselected from the group consisting of copper grains, aluminum grains,nickel grains, and stainless steel grains.

The SiO₂ nano thin film 3 coated on the surface of the wick structure 2is formed of a plurality of SiO₂ nanograins 31 attached to an outersurface of the metal grains 12.

The SiO₂ nano thin film 3 has the characteristic of wetting metal, suchthat when the heat-dissipation unit 1 transfers heat, a working fluid(not shown) inside the heat-dissipation unit 1 can quickly pass throughthe wick structure 2 in the heat-dissipation unit 1 to flow backward.

The SiO₂ nanograins 31 forming the SiO₂ nano thin film 3 have a grainsize ranged between 1 nm and 100 nm, and the SiO₂ nano thin film 3 has athickness ranged between 50 nm and 500 nm. Preferably, the SiO₂nanograins 31 have a grain size ranged between 10 nm and 40 nm, and theSiO₂ nano thin film 3 has a thickness ranged between 200 nm and 40 nm.

Another oxide thin film 8 can be further coated over the SiO₂ nano thinfilm 3, as shown in FIGS. 11 and 11 a. The oxide thin film 8 is form ofa material selected from the group consisting of TiO₂, Al₂O₃, ZrO₂, CaO,K₂O, and ZnO.

Please refer to FIGS. 1, 2, and 4 to 8. As shown, in a first embodimentof a method of manufacturing heat-dissipation unit with heat-dissipationmicrostructure according to the present invention, the following stepsare included:

Step S1: providing a heat-dissipation unit internally defining achamber.

In this step, a heat-dissipation unit 1 with an internal chamber 111 isprepared. The heat-dissipation unit 1 can be a heat pipe as shown inFIG. 1, or a vapor chamber as shown in FIG. 2, or a loop heat pipe (notshown).

Step S2: forming a wick structure on an inner surface of the chamber inthe heat-dissipation unit.

In this step, a wick structure 2 is formed on an inner surface of thechamber 111 in the heat-dissipation unit 1. The first embodiment of themethod according to the present invention is explained based on a wickstructure 2 that is a porous wick structure 2 formed by sintering metalgrains 12. However, it is understood the wick structure 2 can also beformed by other ways without being limited to the way of sintering metalgrains. In the case of the porous wick structure 2, it can be formed bysintering metal grains 12 selected from the group consisting of coppergrains, aluminum grains, nickel grains, and stainless steel grains.

And, the wick structure 2 can be a grooved wick structure as shown inFIG. 1a , a mesh wick structure as shown in FIG. 1b , a copper-powdersintered porous wick structure as shown FIG. 1, or a composite wickstructure combining the copper-powder sintered porous wick structure andthe mesh wick structure (not shown).

Step S3: coating at least an oxide nano thin film on a surface of thewick structure.

In this step, at least an oxide nano thin film 4 is coated on the wickstructure 2 of the heat-dissipation unit 1. The oxide nano thin film 4is formed of a material selected from the group consisting of Al₂O₃,SiO₂, ZrO₂, CaO, K₂O, TiO₂, and ZnO. And, the oxide nano thin film 4 canbe coated on the wick structure 2 through a sol-gel process, which canbe implemented in any one of the following manners: dip-coatingdeposition, settle-coating deposition, spin-coating deposition,spray-coating deposition, brush-coating deposition, and wet-coatingdeposition.

In the illustrated first embodiment of the method of the presentinvention, the oxide nano thin film 4 is coated through the dip-coatingdeposition of the sol-gel process. However, it is understood the oxidenano thin film 4 can also be coated through other deposition manners ofthe sol-gel process without being limited to the dip-coating deposition.As shown in FIG. 8, in the sol-gel process, grains 41 selected from thegroup consisting of Al₂O₃ grains, SiO₂ grains, ZrO₂, CaO grains, K₂Ograins, TiO₂ grains, and ZnO grains are soaked in a water solution 6,and the water solution 6 along with the grains 41 selected from any oneof the above-mentioned materials are poured into a tank 7 and thoroughlymixed, so that the grains 41 are evenly dispersed in the water solution6. Then, immerse a main body 11 of the heat-dissipation unit 1 havingthe wick structure 2 in the water solution 6 contained in the tank 7,and allow the heat-dissipation unit 1 to remain still in the watersolution 6 in the tank 7 for a predetermined period of time. Finally,remove the heat-dissipation unit 1 from the water solution 6 or drainoff the water solution 6 from the tank 7, so that the grains 41 areattached to an outer surface of the wick structure 2.

Step S4: drying the whole heat-dissipation unit.

In this step, the heat-dissipation unit 1 after completion of thedeposition of the oxide nano thin film 4 thereon is subjected to adrying treatment. In the process of drying treatment, theheat-dissipation unit 1 can be placed at room temperature or in asintering furnace (not shown). The sintering furnace can be set to adrying temperature ranged between 50° C. and 200° C. to dry theheat-dissipation unit 1 for 10 to 60 minutes. The higher the dryingtemperature is, the shorter the time for the drying treatment will be.

Step S5: Sintering the whole heat-dissipation unit.

In this step, for the oxide nano thin film 4 to form a uniform film andstably attach to the surface of the wick structure 2 of theheat-dissipation unit 1, the whole heat-dissipation unit 1 is subjectedto a sintering process. In the sintering process, the heat-dissipationunit 1 is placed in a sintering furnace (not shown), and the sinteringfurnace is set to a sintering temperature ranged between 200° C. and800° C. The sintering process continues for 5 to 60 minutes. Finally,the heat-dissipation unit 1 is removed from the sintering furnace.

Step S6: vacuuming the chamber of the heat-dissipation unit.

In this step, air in the chamber 111 of the heat-dissipation unit 1 isevacuated, so that the chamber 111 is in a vacuum state.

Step S7: injecting a working fluid into the chamber of theheat-dissipation unit and sealing an open end of the heat-dissipationunit.

In this step, a working fluid (not shown) is injected into the chamber111 of the heat-dissipation unit 1. The working fluid can be deionizedwater, alcohol, or a type of coolant. Finally, an open end of theheat-dissipation unit 1 is sealed to prevent the working fluid fromleaking out of the heat-dissipation unit 1.

Please refer to FIGS. 1-2, 4-6, and 8-9. As shown, in a secondembodiment of the method of manufacturing heat-dissipation unit withheat-dissipation microstructure according to the present invention, thefollowing steps are included:

Step 1: providing a heat-dissipation unit internally defining a chamber.

In this step, a heat-dissipation unit 1 with an internal chamber 111 isprepared. The heat-dissipation unit 1 can be a heat pipe as shown inFIG. 1, or a vapor chamber as shown in FIG. 2, or a loop heat pipe (notshown).

Step S2: forming a wick structure on an inner surface of the chamber inthe heat-dissipation unit.

In this step, a wick structure 2 is formed on an inner surface of thechamber 111 in the heat-dissipation unit 1. The second embodiment of themethod according to the present invention is explained based on a wickstructure 2 that is a porous wick structure 2 formed by sintering metalgrains 12. However, it is understood the wick structure 2 can also beformed by other ways without being limited to the way of sintering metalgrains. In the case of the porous wick structure 2, it can be formed bysintering metal grains 12 selected from the group consisting of coppergrains, aluminum grains, nickel grains, and stainless steel grains.

And, the wick structure 2 can be a grooved wick structure as shown inFIG. 1a , a mesh wick structure as shown in FIG. 1b , a copper-powdersintered porous wick structure as shown FIG. 1, or a composite wickstructure including any combination of the grooved, mesh, andcopper-powder sintered porous wick structures (not shown).

Step S3: supplying hydrogen for performing an oxidation-reductionprocess on the wick structure.

In this step, an amount of hydrogen (5% H₂+95% Ar₂) is supplied into anatmosphere furnace and the heat-dissipation unit 1 is placed in theatmosphere furnace, so that the wick structure 2 formed on the surfaceof the chamber 111 of the heat-dissipation unit 1 is subjected to anoxidation-reduction process at 700° C. for one hour, in order to removeoxides from the surface of the wick structure 2.

Step S4: coating at least an oxide nano thin film on the surface of thewick structure.

In this step, after completion of the oxidation-reduction process in theprevious step S3, at least an oxide nano thin film 4 is coated on thewick structure 2 of the heat-dissipation unit 1. The oxide nano thinfilm 4 is formed of grains selected from the group consisting of Al₂O₃,SiO₂, ZrO₂, CaO, K₂O, TiO₂, and ZnO grains. And, the oxide nano thinfilm 4 can be coated on the wick structure 2 through the sol-gelprocess, which can be implemented in any one of the following manners:dip-coating deposition, settle-coating deposition, spin-coatingdeposition, spray-coating deposition, brush-coating deposition, andwet-coating deposition.

In the illustrated second embodiment of the method of the presentinvention, the oxide nano thin film 4 is coated through the dip-coatingdeposition of the sol-gel process. However, it is understood the oxidenano thin film 4 can also be coated through other deposition manners ofthe sol-gel process without being limited to the dip-coating deposition.As shown in FIG. 8, in the sol-gel process, grains 41 selected from thegroup consisting of Al₂O₃ grains, SiO₂ grains, ZrO₂, CaO grains, K₂Ograins, TiO₂ grains, and ZnO grains are soaked in a water solution 6,and the water solution 6 along with the grains 41 selected from any oneof the above-mentioned grains are poured into a tank 7 and thoroughlymixed, so that the grains 41 are evenly dispersed in the water solution6. Then, immerse a main body 11 of the heat-dissipation unit 1 havingthe wick structure 2 in the water solution 6 contained in the tank 7,and allow the heat-dissipation unit 1 to remain still in the watersolution 6 in the tank 7 for a predetermined period of time. Finally,remove the heat-dissipation unit 1 from the water solution 6 or drainoff the water solution 6 from the tank 7, so that the grains 41 areattached to an outer surface of the wick structure 2.

Step S5: drying the whole heat-dissipation unit.

In this step, the heat-dissipation unit 1 after completion of thedeposition of the oxide nano thin film 4 thereon is subjected to adrying treatment. In the process of drying treatment, theheat-dissipation unit 1 can be placed at room temperature or in asintering furnace (not shown). The sintering furnace can be set to adrying temperature ranged between 50° C. and 200° C. to dry theheat-dissipation unit 1 for 10 to 60 minutes. The higher the dryingtemperature is, the shorter the time for the drying treatment will be.

Step S6: sintering the whole heat-dissipation unit.

In this step, for the oxide nano thin film 4 to form a uniform film andstably attach to the surface of the wick structure 2 of theheat-dissipation unit 1, the whole heat-dissipation unit 1 is subjectedto a sintering process. In the sintering process, the heat-dissipationunit 1 is placed in a sintering furnace (not shown), and the sinteringfurnace is set to a sintering temperature ranged between 200° C. and800° C. The sintering process continues for 5 to 60 minutes. Finally,the heat-dissipation unit 1 is removed from the sintering furnace.

Step S7: vacuuming the chamber of the heat-dissipation unit.

In this step, air in the chamber 111 of the heat-dissipation unit 1 isevacuated, so that the chamber 111 is in a vacuum state.

Step S8: injecting a working fluid into the chamber of theheat-dissipation unit and sealing an open end of the heat-dissipationunit.

In this step, a working fluid (not shown) is injected into the chamber111 of the heat-dissipation unit 1. The working fluid can be water or atype of coolant. Finally, an open end of the heat-dissipation unit 1 issealed to prevent the working fluid from leaking out of theheat-dissipation unit 1.

Please refer to FIGS. 1-2, 4-6, 8, and 10. As shown, in a thirdembodiment of the method of manufacturing heat-dissipation unit withheat-dissipation microstructure according to the present invention, thefollowing steps are included:

Step 1: providing a heat-dissipation unit internally defining a chamber.

In this step, a heat-dissipation unit 1 with an internal chamber 111 isprepared. The heat-dissipation unit 1 can be a heat pipe as shown inFIG. 1, or a vapor chamber as shown in FIG. 2, or a loop heat pipe (notshown).

Step S2: forming a wick structure on an inner surface of the chamber inthe heat-dissipation unit.

In this step, a wick structure 2 is formed on an inner surface of thechamber 111 in the heat-dissipation unit 1. The third embodiment of themethod according to the present invention is explained based on a wickstructure 2 that is a porous wick structure 2 formed by sintering metalgrains 12. However, it is understood the wick structure 2 can also beformed by other ways without being limited to the way of sintering metalgrains. In the case of the porous wick structure 2, it can be formed bysintering metal grains 12 selected from the group consisting of coppergrains, aluminum grains, nickel grains, and stainless steel grains.

And, the wick structure 2 can be a grooved wick structure as shown inFIG. 1a , a mesh wick structure as shown in FIG. 1b , a copper-powdersintered porous wick structure as shown FIG. 1, or a composite wickstructure including any combination of the grooved, mesh, andcopper-powder sintered porous wick structures (not shown).

Step S3: supplying hydrogen for performing an oxidation-reductionprocess on the wick structure.

In this step, an amount of hydrogen (5% H₂+95% Ar₂) is supplied into anatmosphere furnace and the heat-dissipation unit 1 is placed in theatmosphere furnace, so that the wick structure 2 on the surface of thechamber 111 of the heat-dissipation unit 1 is subjected to anoxidation-reduction process at 700° C. for one hour to remove oxidesfrom the surface of the wick structure 2.

Step S4: coating at least a first oxide nano thin film on the surface ofthe wick structure.

In this step, after completion of the oxidation-reduction process in theprevious step S3, at least a first oxide nano thin film 4 is coated onthe wick structure 2 of the heat-dissipation unit 1. The first oxidenano thin film 4 is formed of grains selected from the group consistingof Al₂O₃, SiO₂, ZrO₂, CaO, K₂O, TiO₂, and ZnO grains. And, the firstoxide nano thin film 4 can be coated on the wick structure 2 through thesol-gel process, which can be implemented in any one of the followingmanners: dip-coating deposition, settle-coating deposition, spin-coatingdeposition, spray-coating deposition, brush-coating deposition, andwet-coating deposition.

In the illustrated third embodiment of the method of the presentinvention, the first oxide nano thin film 4 is coated through thedip-coating deposition of the sol-gel process. However, it is understoodthe first oxide nano thin film 4 can also be coated through otherdeposition manners of the sol-gel process without being limited to thedip-coating deposition. As shown in FIG. 8, in the sol-gel process,grains 41 selected from the group consisting of Al₂O₃ grains, SiO₂grains, ZrO₂, CaO grains, K₂O grains, TiO₂ grains, and ZnO grains aresoaked in a water solution 6. In this third embodiment, SiO₂ grains areselected for use. The water solution 6 and the SiO₂ grains are pouredinto a tank 7 and thoroughly mixed, so that the SiO₂ grains are evenlydispersed in the water solution 6. Then, immerse a main body 11 of theheat-dissipation unit 1 having the wick structure 2 in the watersolution 6 contained in the tank 7, and allow the heat-dissipation unit1 to remain still in the water solution 6 in the tank 7 for apredetermined period of time. Finally, remove the heat-dissipation unit1 from the water solution 6 or drain off the water solution 6 from thetank 7, so that the SiO₂ grains are attached to an outer surface of thewick structure 2.

Step S5: drying the whole heat-dissipation unit.

In this step, the heat-dissipation unit 1 after completion of thedeposition of the first oxide nano thin film 4 thereon is subjected to adrying treatment. In the process of drying treatment, theheat-dissipation unit 1 can be placed at room temperature or in asintering furnace (not shown). The sintering furnace can be set to adrying temperature ranged between 50° C. and 200° C. to dry theheat-dissipation unit 1 for 10 to 60 minutes. The higher the dryingtemperature is, the shorter the time for the drying treatment will be.

Step 6: coating at least a second oxide nano thin film on the previouslycoated first oxide nano thin film.

In this step, at least a second oxide nano thin film 4 is further coatedon the first oxide nano thin film 4 formed in the step S4. In the thirdembodiment, the second oxide nano thin film 4 coated on the first oxidenano thin film 4 is formed of TiO₂ grains. However, it is understood thesecond oxide nano thin film 4 can also be formed of other oxide grainswithout being limited to the TiO₂ grains. Further, the second oxide nanothin film 4 can be coated on the first oxide nano thin film 4 throughthe sol-gel process, and the sol-gel process can be implemented in anyone of the following manners: dip-coating deposition, settle-coatingdeposition, spin-coating deposition, spray-coating deposition,brush-coating deposition, and wet-coating deposition.

Step 7: drying the whole heat-dissipation unit.

In this step, the heat-dissipation unit 1 after completion of thedeposition of the second oxide nano thin film 4 thereon is subjected toa drying treatment. In the process of drying treatment, theheat-dissipation unit 1 can be placed at room temperature or in asintering furnace (not shown). The sintering furnace can be set to adrying temperature ranged between 50° C. and 200° C. to dry theheat-dissipation unit 1 for 10 to 60 minutes. The higher the dryingtemperature is, the shorter the time for the drying treatment will be.

Step S8: Sintering the whole heat-dissipation unit.

In this step, for the second oxide nano thin film 4 to stably attach tothe surface of the first oxide nano thin film 4, the wholeheat-dissipation unit 1 is subjected to a sintering process. In thesintering process, the heat-dissipation unit 1 is placed in a sinteringfurnace (not shown), and the sintering furnace is set to a sinteringtemperature ranged between 200° C. and 800° C. The sintering processcontinues for 5 to 60 minutes. Finally, the heat-dissipation unit 1 isremoved from the sintering furnace.

Step S9: vacuuming the chamber of the heat-dissipation unit.

In this step, air in the chamber 111 of the heat-dissipation unit 1 isevacuated, so that the chamber 111 is in a vacuum state.

Step S10: injecting a working fluid into the chamber of theheat-dissipation unit and sealing an open end of the heat-dissipationunit.

In this step, a working fluid (not shown) is injected into the chamber111 of the heat-dissipation unit 1. The working fluid can be deionizedwater, alcohol, or a type of coolant. Finally, an open end of theheat-dissipation unit 1 is sealed to prevent the working fluid fromleaking out of the heat-dissipation unit 1.

Please refer to FIGS. 4, 5 and 6, which are scanning electron microscope(SEM) images of the heat-dissipation microstructure manufacturedaccording to the present invention. As shown in FIG. 4, the manufacturedheat-dissipation microstructure is a copper wick structure 5 formed bysintering a plurality of copper grains 51, so that the copper wickstructure 5 is a copper porous wick structure.

As shown in FIGS. 5 and 6, at least an oxide nano thin film 4 isuniformly coated on the surface of the copper wick structure 5 shown inFIG. 4, including pores on the copper wick structure 5.

The oxide nano thin film 4 with wettability, such as a SiO₂ nano thinfilm as shown in FIG. 5, is uniformly coated on the surface of thecopper wick structure 5, and the oxide nanograins 41 forming the oxidenano thin film 4 have a relatively uniform grain size.

In the above embodiments of the present invention, the followingmaterials are used:

-   -   1. Nano-sol surface pretreatment chemical (Product Number T-80):        It is supplied by Chung-Hsin Technological Consultants, Inc.        (Taiwan) and mainly contains 0.8% of TiO₂ nanoparticles having a        particle size ≦10 nm and a type of surfactant. Its product        characteristics include a specific gravity of 1.01±0.03; a flash        point higher than 100° C.; in the form of a golden and        transparent liquid; a pH value of 7.0±0.5; and an operating        temperature of 30±5° C.    -   2. Nano-sol surface pretreatment chemical (Product Number        LS-150): It is supplied by Chung-Hsin Technological Consultants,        Inc. (Taiwan) and mainly contains 1.5% of SiO₂ nanoparticles        having a particle size ranged between 10 nm and 40 nm. Its        product characteristics include a specific gravity of 1.03±0.03;        a flash point higher than 100° C.; in the form of a colorless        and transparent liquid; a pH value of 7.0±0.5; and an operating        temperature of 40±2° C. This material can be coated and baked        (sintered) on a substrate material to form an inorganic film of        SiO₂ on the surface of the substrate material, so that the        substrate material has smooth surface, and is easily cleanable        and hydrophilic.    -   3. Nano-sol surface pretreatment chemical (Product Number        A-100): It is supplied by Chung-Hsin Technological Consultants,        Inc. (Taiwan) and mainly contains 1.0% of Al₂O₃ nanoparticles        having a particle size ≦10 nm. Its product characteristics        include a specific gravity of 1.01±0.03; a flash point higher        than 100° C.; having a colorless and transparent appearance; a        pH value of 7.0±0.5; and an operating temperature of 10-40° C.

The present invention has been described with some preferred embodimentsthereof and it is understood that many changes and modifications in thedescribed embodiments can be carried out without departing from thescope and the spirit of the invention that is intended to be limitedonly by the appended claims.

What is claimed is:
 1. A heat-dissipation unit with heat-dissipationmicrostructure, comprising a main body internally defining a chamber, awick structure formed on an inner surface of the chamber, and at least aSiO₂ nano thin film coated on a surface of the wick structure; whereinthe SiO₂ nano thin film is formed of a plurality of nanograins, whereinthe wick structure is formed of a material selected from the groupconsisting of copper, aluminum, nickel and stainless steel.
 2. Theheat-dissipation unit with heat-dissipation microstructure as claimed inclaim 1, wherein the wick structure is selected from the groupconsisting of a grooved wick, a mesh wick structure, a copper-powdersintered porous wick structure, and a composite wick structure includingany combination of the grooved, mesh, and copper-powder sintered porouswick structures.
 3. The heat-dissipation unit with heat-dissipationmicrostructure as claimed in claim 1, wherein the SiO₂ nano thin filmhas a thickness ranged between 10 nm and 500 nm.
 4. The heat-dissipationunit with heat-dissipation microstructure as claimed in claim 1, whereinthe SiO₂ nano thin film is coated on a whole surface of the wickstructure.
 5. The heat-dissipation unit with heat-dissipationmicrostructure as claimed in claim 1, wherein the heat-dissipation unitis selected from the group consisting of a vapor chamber, a heat pipe,and a loop heat pipe.
 6. A heat-dissipation unit with heat-dissipationmicrostructure, comprising a main body internally defining a chamber, awick structure formed on an inner surface of the chamber, and at least aSiO₂ nano thin film coated on a surface of the wick structure; whereinthe SiO₂ nano thin film is formed of a plurality of nanograins, whereinthe nanograins forming the SiO₂ nano thin film have a grain size rangedbetween 1 nm and 100 nm.
 7. A heat-dissipation unit withheat-dissipation microstructure, comprising a main body internallydefining a chamber a wick structure formed on an inner surface of thechamber and at least a SiO₂ nano thin film coated on a surface of thewick structure; wherein the SiO₂ nano thin film is formed of a pluralityof nanograins, wherein the SiO₂ nano thin film is further coated withanother oxide thin film.
 8. The heat-dissipation unit withheat-dissipation microstructure as claimed in claim 7, wherein the oxidethin film is formed of a material selected from the group consisting ofTiO₂, Al₂O₃, ZrO2, CaO, K₂O, and ZnO.